BasicAA: Move BasicAAResult::alias out-of-line. NFC

This makes the header more readable and cleans up some unnecessary
header differences between NDEBUG and !NDEBUG.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@248462 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed